In order to remedy the drawbacks of landing gear with metal skids and crosspieces as far as weight and irreversible deformation are concerned, it has already been proposed, in French Pat. No. 1 272 208, to use as glider or helicopter skids resilient members of synthetic material in bar form, allowing high energy absorption. These members in bar form comprise an upper boom and a lower boom, intended to absorb the tensile or compressive stresses and produced from synthetic material reinforced by glass fibre mat, as well as thrust walls connecting the two booms and composed of glass fibre reinforcements inclined at 45.degree. to the direction of the axis of the bar, the reinforcements being embedded in the synthetic material and being connected to the booms. The bar thus formed therefore is substantially in the shape of an elongate box form provided internally with a solid core of material with a low specific weight, such as a synthetic foam material with closed cells, in order to increase the rigidity of the walls.
In French Pat. No. 1 296 381, there have already been proposed skid landing gear for light helicopters comprising struts fixed to the fuselage, carrying skids and consisting of a very resilient laminated material, for example a synthetic material which is fibre-reinforced but in which breakage occurs without previous plastic deformation, the struts being arranged so that the skids move away from each other when sliding on the ground during landing.
Finally, it is a known procedure to mount the landing gear struts resiliently on the members connecting them to the fuselage of the aircraft. This type of mounting is described in U.S. Pat. No. 2,539,817, which relates to a ski device for a light aircraft landing gear, in which the struts carrying the skis are resiliently mounted by means of resilient sleeves housed in bushes solidly connected with the struts and in which there are engaged shafts solidly fixed to the structure of the fuselage.
If the embodiments in composite materials covered by the two French Patents cited above do offer the advantage of a considerable gain in mass compared with landing gear with metal skids, the fact remains that by reason of the absence of an inherent elastic limit of the composite material, the kinetic energy due to the impact is absorbed by the elastic deformation of the skids and/or of the landing gear struts for all kinds of landing. Under these conditions, the low energy absorption capacity of the composite materials, in order to keep the same capacity as the metal landing gear, leads either to allowing the same deformation as on the metal landing gear, the consequence of which is an increase in the stress transmitted by the landing gear to the structure of the fuselage, or to allowing greater deformation, in order that the stress transmitted to the fuselage structure should be substantially the same as with metal landing gear, the consequence of which is a softening of the landing gear structure, and therefore an increased risk that the struts and/or the skids of the landing gear will collapse or break before having absorbed the impact energy.